The present invention relates generally to agricultural implements and, more specifically, to a spring trip standard for tillage implements.
Spring trip standards typically include a mounting bracket attached to a rectangular toolbar and extending upwardly and rearwardly to a downwardly and forwardly directed spring abutment surface. A spring is compressed between the abutment surface and an upwardly directed spring abutment surface on a member pivotally connected to the lower portion of the bracket, and a tool supporting shank is fixed to the member. A tension link assembly extends from the shank supporting member through the spring and through an aperture in the spring abutment surface on the bracket to adjust the preloading of the spring and vary the vertical position of the tool connected to the shank. Such an assembly is shown by way of example in U.S. Pat. No. 3,700,039 entitled SPRING TRIP SHANK ASSEMBLY. This type of shank assembly provides good trip force characteristics but has numerous parts and is expensive and time-consuming to assemble and repair. Previously available assemblies, particularly those with numerous tension link or spring support components such as pins, straps, spacers and washers, typically require extensive instructions for assembly and disassembly.
In some shank assemblies, the tension link reduces forces on the pivot area in the at rest position, thereby introducing some looseness in the pivot joints which often is perceived as a quality disadvantage and which causes the tool to have some lateral shift during operation. Often the precompression of the spring when the tool is in the normal operating position is not sufficient to prevent some continual tripping action.
In commonly assigned U.S. Pat. No. 6,250,398 entitled SPRING TRIP STANDARD, a spring trip arrangement is described which does not require a tension link. In commonly assigned U.S. Pat. No. 6,065,548 entitled SPRING TRIP STANDARD HAVING REDUCED SPRING BUCKLING FORCES, spring seat structure is described for providing generally perpendicular alignment of the lowermost coil of the spring relative to the centerline of the coil spring in both the field-working and the tripped positions so that spring buckling and spring fatigue caused by buckling are reduced. Upstop limit for the shank is provided by the spring when the spring coils stack against each other. To prevent spring coils from slipping past one another and causing permanent spring deformation, a spring stop arrangement described in commonly assigned U.S. Pat. No. 6,250,397 is provided. The stop arrangement also includes a downstop limit which establishes the lowermost field-working position of the shank and pitch of the tool mounted on the shank. Although the above-described arrangement reduces cost and increases reliability compared to at least most previously available spring trip shank assemblies, the lowermost position of the shank and pitch of the tool cannot be easily adjusted. Therefore, setting up the shanks for proper depth and tool angle has been a continuing problem with the assemblies that do not have a tension link to adjust the lowermost position of the shank. The ability to make quick and accurate adjustments of a plurality of such assemblies across the width of an implement has heretofore been unavailable.
It is therefore an object of the present invention to provide an improved spring trip assembly for an implement. It is a further object to provide such an assembly which overcomes most or all of the aforementioned problems.
It is a further object of the present invention to provide an improved spring trip assembly which has fewer parts and is lower in cost than most previously available shank assemblies and yet which facilitates shank adjustment. It is another object to provide such an assembly wherein tool pitch can be quickly and easily adjusted. It is still another object to provide such an assembly which is simple and inexpensive in design and manufacture and which does not require a tension link.
It is still another object of the invention to provide an improved spring trip shank assembly having a positive downstop independent of any tension link but yet which has an adjustable lowermost position. It is another object to provide such an assembly which is adjustable and wherein a plurality of the assemblies can be quickly and easily adjusted relative to each other. It is yet another object to provide such an assembly including a visual indicator for determining shank settings.
It is a further object of the present invention to provide a spring trip shank assembly which is simple and inexpensive in construction and which includes an eccentric mechanism strategically located to allow an operator to quickly and easily select from a variety of tool pitch positions. It is a further object to provide such an assembly which allows accurate adjustment of a plurality of assemblies across the width of an implement. It is still another object to provide such an assembly which includes a spring assembly without a tension link and which facilitates construction of the assembly with a one-piece shank support which includes a pivot area and fixed stop structure.
A spring trip standard for a tillage implement includes a coil spring compressed between an upper spring-abutting surface on the mounting bracket and a lower spring abutment surface on a casting which is connected by a transverse pivot to the mounting bracket. A tool-supporting shank is connected to the casting and biased downwardly into a ground working position by the spring. The casting includes a first integral stop extending forwardly from the pivot. The stop contacts the bottom of the bracket when the shank is in the ground working position so that a tension link between the bracket and casting is eliminated. The standard also includes a second stop to limit upward pivoting to a maximum tripped position wherein the spring is in or approaches a fully compressed condition but is not forced into an overly compressed condition wherein spring deformation occurs. Both the downstop and upstop functions are provided by a single casting.
To provide shank and tool pitch adjustment for the fixed downstop structure, the shank pivot area includes an eccentric mechanism with calibrated pitch positions for varying the location of the shank pivot relative to the downstop. The mechanism for varying pivot location includes a bushing with an eccentric bore inserted though the shank pivot area. A keyway in the bushing receives a threaded bolt with a mating key. The eccentric bore is aligned with holes in the standard mounting bracket, and the bolt and key are inserted through the bracket holes and the bore. A captive nut fastens the mechanism in position between the sides of the mounting bracket for the desired shank pitch. Multiple holes or elongated slots in the mounting bracket sides are not required for making the changes in shank pivot location.
To change pitch position, the nut is loosened and a wrench is positioned on the bolt to rotate the bolt and the bushing and thereby change the shank pivot location relative to the downstop. When the desired pitch is achieved, the nut is retightened. Incremental marks located on the mounting bracket and a notch on the bolt head which can be aligned with a selected one of the marks provide an easily readable indication of the selected pivot location so a plurality of the assemblies can be adjusted to the same pitch quickly and easily. The assembly is also inexpensive and simple in design and overcomes problems of adjusting a shank assembly with a fixed downstop.
A one-piece shank support structure which includes a pivot area and fixed stop may be used for reducing the number of parts and for ease of assembly while still retaining the pitch adjustment feature. The stop can contact a solid portion of the mounting bracket or implement frame adjacent the bracket since there is no need for an intermediate member to change downstop location. Adjustment structure that otherwise would be necessary and subject to looseness and wear at a high impact stop location is avoided.
These and other objects, features and advantages of the present invention will become apparent to one skilled in the art upon reading the following detailed description in view of the drawings.